Twist-on, spin-on, disposable type filters are used in numerous liquid and pneumatic applications throughout the agricultural, mobile, commercial and industrial market places. Prior art twist-on disposable filter products are manufactured using a thin gauge metal can, or housing, made by the deep-draw forming of malleable metals. This technique limits the structural capabilities of current twist-on, spin-on, type products to the production capabilities of the metal forming industry and to the molecular characteristics of a limited number of specific malleable metals. Prior art uses a stamped steel or cast cover plate to secure the can to a mounting and distribution head assembly. This plate typically having a threaded center hole is spot welded and/or crimp sealed to a deep-drawn can. These techniques for sealing and connecting the can to the plate, plus the structural limits of thin gauge malleable metals, generally restrict the applicational uses of prior art twist-on, spin-on disposable filters. Some new high pressure, high-strength, disposable filter housings with burst pressure ratings in the 1,000 psi range have been developed for some narrowly defined markets and applications. However, even these newer high-strength filters remain applicationally limited because of their continued use of deep-drawn metal cans.
Another typical design common to prior art twist-on, spin-on, type disposable filters is the necessity of installing a separate filter element as well as various separator devices, in a housing can. A separate and segregated internal filter element cartridges is subject to different cyclical operational loads than those experienced by the filter housing. Current internal filter cartridge designs do not properly protect against seal distortion and wear deterioration caused by applicational flow dynamics and vibration. Such seal distortion and wear deterioration lessens a filters contamination removal efficiency by allowing contaminated fluid to by-pass the filter medium.
Examples of prior art limitations can be found in U.S. Pat. No. 4,719,012 and more recently U.S. Pat. No. 4,743,374 issued as an improvement over earlier U.S. Pat. No. 4,369,113. Each of these designs incorporates the continued use of deep-drawn thin gauge metal can having a separate and segreated internal filter cartridge. Burst pressure ratings are in the 1,000 psi range with rated fatigue pressure in the 500 psi range. These prior art pressure limitations continue to leave a major product void in the high-strength twist-on disposable filter market.
Thus, a need exists for a structurally improved twist-on, spin-on, type disposable filter with higher pressure capability, a better fatigue rating, one that eliminates the need for a segregated internal filter cartridge, and a filter product that decreases by-passing fluid losses caused by distorted or deteriorated internal filter seals. The present tube filter invention is designed to overcome one or more of the problems as set forth above.